Many consumer products, vehicles and other apparatus, are equipped with a fuel tank for liquid fuel, such as gasoline, kerosene, or other combustible liquids. Such volatile liquid fuels are inherently dangerous and present a severe fire hazard, especially during refueling operations when the fuel cap is removed from the fuel tank. With many devices, it is important to replace the fuel cap on the fuel filler cap receptacle prior to resuming operation of the device.
If a fuel cap is not replaced on a fuel tank, fuel can spill out of the fuel tank refilling opening, and fumes can emanate from the fuel tank opening. Ignition of vapors or liquid fuel flowing from the fuel tank can cause fuel in the fuel tank to also ignite.
A latent danger exists when a fuel tank is closed by a cap which is not the properly matched cap for the fuel tank, but a similarly sized or improperly gasketed cap. If the improper cap is placed on a fuel tank, fuel can leak from the fuel tank when fuel is emitted with air and if exposed to a spark it can result in a fire or explosion. If the wrong cap is placed on a fuel tank, fuel leakage can occur even though an improper fuel cap was assembled to the fuel tank opening.
Certain devices present foreseeable risk of injury, fire or explosion if operated when the fuel cap is removed. One example of such an inherently dangerous device is a liquid fuel burning heater, such as a kerosene heater or kerosene burning light. It would be desirable to provide a mechanism for inhibiting operation of such devices when the fuel cap is removed because it is known that fumes from spilled fuel or otherwise emanating from the fuel tank can be ignited by the open flame of the heater. A further safety feature that would be desired would be to prevent operation of an apparatus if an improper fuel cap/fuel tank combination is attempted. An interlocking mechanism would have to be a mechanical, "explosion-proof" or "non-spark producing" device.
Liquid fuel burning heaters generally include a fuel tank which supplies fuel through a fuel feedline to a reservoir containing a wick. The combustion rate of the wick is controlled by raising and lowering the wick within the reservoir. Once ignited, greater exposure of the wick to the oxygen of the atmosphere results in increased heat, while submerging the wick within the reservoir reduces the heat generated. If the wick is completely submerged in the reservoir, the flame is extinguished due to oxygen deprivation.
Improper use of such liquid fuel burning heaters inherently presents the well recognized, latent and foreseeable hazard of a sudden, unexpected or uncontrolled fire or explosion. For instance, the use of an inappropriate fuel, such as gasoline, in a kerosene heater can cause excessive flames or a sudden and unexpected, delayed flare up in the heater. Additionally, the use of contaminated fuel in the heater can lead to the excessive flames or a sudden and unexpected, delayed flare up or explosion. There is a foreseeable risk that highly combustible fuel could escape from the reservoir or tank if the fuel cap is not replaced or an improper fuel cap is used. The risk of uncontrolled burning and fire is exacerbated if such heaters are refuelled while operating. It is foreseeable that uncontrolled burning could result from these and other conditions creating intense heat and catastrophic damage.
Certain purported safety features have been included in some prior art devices, including those designed to prevent against tip over of the device having a liquid fuel tank and others which sense excessive heat and cause such devices to shut down. These devices are not proactive in that a fire must begin to burn out of control before they will function. For example, none of the prior art theaters include an automatic apparatus which will effectively eliminate the chance of fire due to fuel spillage during tank refilling.
Accordingly, it is an object of the present invention to provide a heater which will sense the removal of the cap for refilling and proactively eliminate the chance of unwanted combustion of fuel spilled during refuelling.
It is a further object of the present invention to provide a proactive cap presence mechanical interlock mechanism which is mounted outside of the vapor environment in a recessed location so that it is not easily defeatable. It is another object of the present invention to provide a mechanism which is moved in response to the removal of a fuel cap and transmits such movement through a mechanical linkage to a remotely located mechanism for inhibiting operation of the device. For example, in conjunction with liquid fuel burning heaters the present invention provides a mechanical linkage mechanism which will cause the wick to become submerged in the fuel reservoir, thereby extinguishing flames during refueling.
It is still another object of the present invention to provide such a mechanism that will prevent combustion in the absence of a matched fuel tank cap.